Toxic waste still leaking from Vic creek

Camera IconA toxic waterway spill linked to a factory fire at West Footscray last year is still being treated.

A tributary of Melbourne's Yarra River is slowly trickling back to full health after a toxic chemical spill linked to a fire at a factory storing hazardous materials.

Tests from Stony Creek, which runs through several inner west Melbourne suburbs, showed high levels of acetone, disinfectants, herbicides, fire retardant chemicals and heavy oils following a blaze at West Footscray in August last year.

The health of the creek has improved slightly but full remediation is a long way off, Environmental Protection Authority water scientist Liam Metzeling told AAP on Tuesday.

"It's the worst I've ever seen and I've been working at the EPA almost 30 years," he said.

Hundreds of "nasty chemicals" had been found in the waterway following the fire which caused acrid smoke to blanket parts of the city, forced schools and businesses to shut and sent contaminated run-off into Stony Creek.

"We tested in the order of 250 compounds after the blaze and the peaks for a lot of them were 'very high' in the immediate days after the fire but that has declined significantly," Mr Metzeling said.

"But that doesn't mean the creek is clean by any means."

Dredging and other clean-up works are underway at the worst-affected area, directly behind the factory.

The fire is subject to a coronial investigation.

Some wildlife has returned further downstream but toxins remain in the sediment and can be brought to the surface by heavy rain, causing a stench.

"I can understand people thinking (the clean up is) taking a long time; it's a very challenging thing to do because there were so many nasty chemicals involved," Mr Metzeling added.

News of the damage comes as the authority investigates two more dangerous stockpiles of waste uncovered in suburban Melbourne at Derrimut and Altona.

"The community has a right to expect hazardous and industrial waste is managed to a high standard that meets regulations, which is why EPA conducts regular inspections ... to hold businesses to account and make sure they're doing the right thing," an authority spokesman said.

The Briggs Drive site at Derrimut was discovered breaching permit and planning regulations in January by illegally storing waste and the stockpile must be removed.

It's not the first time it has been investigated, with the facility inspected seven times since July 2017.

The Altona site was inspected in March and recyclable waste was found being stockpiled.